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State continues preparation for the soybean rust battle

MISSISSIPPI STATE -- Mississippi's agricultural industry is poised to minimize the second year of soybean rust after the disease overwintered in Florida and northeast Mexico.

“As of late April, we haven't seen any rust in the state this year,” said Alan Blaine, soybean specialist with the Mississippi State University Extension Service. “Winter weather beat it back to where it overwintered in south Florida.”

Asian soybean rust entered Mississippi in 2005 and was found in two sentinel plots and later in three growers' fields in southeast Mississippi. The spores of the fungus can spread rapidly on the wind and almost completely destroy plants and yields under optimum conditions when untreated. The country has been on high alert for the disease for the past few years.

“The rust came in so late that it didn't cause any damage last year,” Blaine said. “The growers sprayed fungicide, plus the weather was not favorable for the rust, so it was of no consequence last year. I don't see it being any more of a problem this year in Mississippi.”

Billy Moore, an Extension plant pathologist emeritus, oversees the state's sentinel plots. There are 17 plots of soybeans planted between March 1 and March 9 which are monitored at least weekly for indications of rust. In addition to these sentinel plots, producers' fields are checked regularly, as are plots of kudzu and other known hosts of the fungus.

“Soybeans are most susceptible to rust during the reproductive stages. We plant the sentinel plots earlier than producers plant their fields so our plots reach these stages ahead of producers' crops,” Moore said.

Sentinel plots are scattered from Lee County in northeastern Mississippi to Jackson County in the southeastern corner, across the coastal counties and up the Mississippi River to Coahoma County. The Mississippi Soybean Promotion Board is heavily involved in funding these early detection efforts and in the distribution of information about the disease.

“In my 40 years as an Extension plant pathologist, I have never seen a more cooperative effort between all the state and federal agencies, the northern and southern producers, industry, Extension and research,” Moore said. “There have been no turf battles and everybody has concentrated on trying to solve this problem for our producers.”

A solution does seem to exist. While rust can enter Mississippi from Mexico and Florida on wind currents, early detection measures are in place to note its arrival.

In addition to regular monitoring of the sentinel plots, Moore said five wet traps are being set up to capture rust spores washed out of the sky in rain. Another 10 dry traps will be placed across the southern part of the state to try to detect the airborne spores.

Last year when the disease was detected, Extension specialists called for application in south Mississippi of fungicides labeled to fight soybean rust. Producers complied, and the fungicides and dry, hot weather limited the rust's impact. Experts are ready to make these recommendations again this year if the situation warrants.

The last factor protecting Mississippi from rust becoming a larger problem is that its host plants are killed during the winter months. It appears rust will have to be blown in each year from warmer areas where hosts survive the winter.

Although rust may enter the state this year, the spring weather has been unseasonably dry and hot. Rust spores need moisture for germination and plant infection. Unless favorable conditions exist, rust cannot become established in Mississippi soybeans, and yield losses will be low. Intense solar radiation limits the fungus' ability to survive long-distance spread.

With active searches to detect the first appearance of the disease and fungicides to prevent it from developing, those involved in the rust battle are optimistic that Mississippi producers can win.

“The growers are perhaps more informed on soybean rust than any other disease that has existed on Mississippi crops,” Moore said.

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